What does a guy mean when he says he sees you as more than a friend but less than a girlfriend?

I am in high school and my really close guy friend told me that he liked me. A couple of mutual friends told me that he really liked me and that he never felt this way about a girl before. He is very shy and none of our mutual friends knew about his crush until a few days before I found out. They told me that it was really bothering him and he wanted to tell me but he was really scared and didn't know how to tell me. We dated very briefly. Our mutual friends told me how he was so excited and happy to date me. When we started, it was awkward and I just assumed it was because it was the beginning stages of the relationship. We were still acting like how we were before as friends, but it felt kind of weird. Eventually, I finally felt like the awkwardness was going away, but then he messaged me and told me how we needed to talk. He said he did agree that we were awkward and maybe we should go slower. The thing is, we were going slow. He then proceeded to say that maybe we should just be friends for right now. I was so confused by the situation since he supposedly liked me so much. He had told our friend that he thought I was an amazing friend and he was scared if anything ever happened in our relationship, that he would lose me, which he doesn't want. It's been about a month since this all happened and he recently told the same friend that he sees me as more than a friend but less than a girlfriend. I don't understand what he means by that. I know he is inexperienced with relationships. I think that he might not know how to handle a relationship since he's inexperienced? Or maybe he just values our friendship too much? What do you think?